1. Field of the Invention
The present invention relates to document distribution networks and particularly to a control mechanism for controlling the distribution of documents in a facsimile distribution system.
2. Prior Art
The use of facsimile communication systems for distributing documents is well known in the prior art. Such systems include one or more transmitting terminals, one or more receiving terminals, and a communication link interconnecting the terminals. Usually the transmitting terminal includes a raster input scanner which scans a document and generates a video stream of pixels representing the informational contents of the document. The video stream of pixels is digitized, imposed on a carrier signal, and transmitted via the communication link to the receiving terminal. A typical receiving station includes a demodulator which recovers the digitized data. The digitized data is utilized by a printer to reproduce a copy (facsimile) of the transmitted document. Facsimile communication systems operate either in a point-to-point mode or a distributive mode. When operating in the point-to-point mode, the transmitting terminal communicates directly with a receiving terminal. When operating in the distributive mode, data from the transmitting terminal is redistributed by other agents on a communication link.
To facilitate the control of data, the communication links have nodes or switching junctions. The nodes are usually coupled to host controllers, such as computers. The primary function of the host is to control the flow of data through the communication link and to ensure that the link operates at maximum efficiency. To this end, data are often stored at a host and transmitted at a more opportune time. Other well-known functions are performed by the host but will not be described because they are not germane to the present invention.
Substantial effort and cose have been expended to automate facsimile systems. Automation dictates that these systems function with a minimum operator intervention. To achieve this, the prior art has adapted several devices or techniques to control the systems. In one prior art technique, a coded information (CI) input terminal, such as a keyboard, is used to key controlled information into the system. Such control information includes recipient addresses, distribution commands, printing commands, scanning commands, etc. Although this approach works well for its intended purpose, it undermines the automatic philosophy because an operator is needed to enter the controlled information.
U.S. Pat. Nos. 3,594,495, 4,086,443 and 4,207,598 disclose another technique used in the prior art to automate document distribution. U.S. Pat. No. 3,594,495 describes a radio facsimile postal system including a device for transmitting signals representative of a written message and a radio facsimile recorder to receive the transmitted signals. The addressee is identified by unique code signals embedded in the transmitted signals. Each recorder is conditioned to respond to a different code signal. Therefore, the transmitted message will only be reproduced by the recorder which is conditioned to respond to the transmitted code.
U.S. Pat. No. 4,207,598 describes an automatic mail system wherein a television camera scans a document and the information is transmitted to a storage device in a telephone exchange. The identity of the addressee is sent to the exchange where it is deciphered and a path to the destination is set up automatically.
U.S. Pat. No. 4,086,443 describes the use of a job separation sheet which may be mark-sensed by a facsimile scanner to detect the address of the receiver.
U.S. Pat. No. 4,058,672 shows yet another example of the prior art control techniques. The patent discloses a data communication network where data blocks are placed in packets along with addresses and priority information. The communication network then transmits the packets in the most efficient way possible. Upon receiving the packets, the receiver puts the data message back together. Although the different automatic techniques described in the patents seem to be a step in the right direction, none of these techniques disclose or suggest a method wherein the sender controls the entire system.